Answer:
(x+1)(x-3i) (x+3i)
Step-by-step explanation:
x^3 + x^2 + 9x+9
We will use factor by grouping
Factor out x^2 from the first group and 9 from the second group
x^3 + x^2 + 9x+9
x^2( x+1) + 9(x+1)
Factor out (x+1)
(x+1) ((x^2+9)
Now factor x^2+9
x^2 -(3i)^2 = (x-3i) (x+3i)
Replacing this
(x+1)(x-3i) (x+3i)
